Out of plane expansion of PFSA membranes for fuel cell applications

Michael H. SantareA critical element of a hydrogen fuel cell is the proton???exchange membrane. Its unique properties allow it to conduct the protons of hydrogen atoms, while excluding the electrons to create an electrical charge. A fuel cell???s overall durability and conductivity is in large part determined by the properties of the membrane. This research involves the use of perfluorosulfonic acid (PFSA) membranes, a common type of proton???exchange membranes. When any material is heated or cooled, it typically expands or contracts and, if this dimensional change is constrained, it causes a stress in the material. This stress, when applied cyclically over a period of time, leads to damage and eventual failure of the material. Hence over time as the membrane of a fuel cell is subjected to changes in temperatures, the membrane experiences a decrease in its durability and conductivity. Also, in order for these membranes to properly function, a certain level of hydration is needed. PFSA membranes are hydrophilic, and easily absorb water from the chemical reaction it sustains and from the atmosphere. Thus the absorption of the water causes the membrane to swell and result in dimensional changes in its thickness and in???plane dimensions. Similarly to thermal expansion, when this swelling strain is constrained, it causes a stress in the material, and ultimately results in damage or failure when applied cyclically over time. Therefore the goal of this research is to understand how PFSA membranes expand and contract over a range of temperatures from ???40?? C to 105?? C, as well as with varying humidities in the range of 30% to 100%.Mechanical Engineerin